The wrong application of Chi Sao is believing you can stick to your opponent while fighting.

Well, unless your opponent is playing the same game,it's not possible. While your trying to stick or stay connected to your opponent bridge he will be striking you..You will be at least a half a beat behind him at all times, however, having a high level of skill in Chi Sao, can gives you a big advantage. But IMO to apply it that way is a gross misunderstanding and a mistake..You should be hitting your opponent not trying to play a Chi Sao game. Use your skills to strike your opponent and don't waste anytime..Use the skills you've developed to assist you to control and interrupt your opponent's movement, but your primary focus should be on striking him. Don't look for a bridge to cross over,just hit your opponent.